A U.S. Army Black Hawk helicopter went down in northern Iraq, killing all 12 Americans believed to be aboard in the deadliest crash in nearly a year, while five U.S. Marines died in weekend attacks, the military said Sunday.

The latest deaths followed an especially bloody week in which about 200 Iraqis and a dozen U.S. troops were killed. Iraqi politicians, meanwhile, claimed headway in forming a stable coalition government following the Dec. 15 elections, whose final results may be released this week.

U.S. military officials said the UH-60 Black Hawk crashed just before midnight Saturday about seven miles east of Tal Afar, a northern city near the Syrian border that has seen heavy fighting with terrorists.

"All (those killed) are believed to be U.S. citizens," military spokesman Lt. Col. Barry Johnson said.

He did not say what caused the crash, but bad weather has wracked most of Iraq.

The Black Hawk was part of a two-helicopter team providing support for the 101st Airborne Division and was flying between bases when communications were lost, the military said. After a search, the helicopter was found about noon Sunday, the military said.

The helicopter was part of Task Force Band of Brothers and attached to the 101st Aviation Brigade, but Maj. Tom Bryant, spokesman for the division's 3rd Brigade, said the helicopter was not from Fort Campbell, Ky., and belonged to another unit.

Bryant could not say what unit the helicopter belonged to or whether any soldiers from the 101st were aboard. Master Sgt. Terry Webster of division public affairs could not identify what unit operated the helicopter.

It was the deadliest helicopter crash in Iraq since a CH-53 Sea Stallion went down in bad weather in western Iraq on Jan. 26, 2005, killing 31 U.S. service members.

In Saturday's crash, records indicated that eight passengers and four crew members were aboard.

Three Marines were killed Sunday by small arms attacks in Fallujah, 40 miles west of Baghdad, the military said. Two other Marines were killed Saturday by roadside bombs in separate incidents, the military said.

With the latest Marine deaths, at least 2,199 members of the U.S. military have died since the war started in 2003, according to an Associated Press count. That toll did not include those killed aboard the Black Hawk.

In other violence Sunday, five people died in separate attacks in Baghdad, including a policeman killed by a suicide car bomber targeting an Interior Ministry patrol. Seven others were wounded.

Meanwhile, a French engineer abducted Dec. 5 apparently was dumped on a Baghdad street by his fleeing captors and recovered by U.S. troops, who turned him turned over to the French Embassy on Sunday, according to Iraqi police and the French Foreign Ministry in Paris.

Bernard Planche, 52, was kidnapped on his way to work at a water plant. Planche worked for a non-governmental organization called AACCESS and was found Saturday night near a checkpoint in the Abu Ghraib neighborhood. His captors had demanded the withdrawal from Iraq of French troops — even though the country has none in Iraq.

The French Foreign Ministry said Planche should be returning to France shortly.

French Prime Minister Dominique de Villepin thanked U.S. authorities, as well as French diplomatic and intelligence officials, for their help in Planche's "liberation during a securing operation."

Terrorists have kidnapped more than 250 foreigners in the past two years, aiming to force U.S.-led troops to leave Iraq or prevent Arab nations from strengthening their ties with Baghdad.

The leader of Iraq's main Sunni Arab political group said after meeting President Jalal Talabani that significant headway had been made in efforts to form a government of national unity.

"Talabani and I have an identical point of view regarding the formation of a national unity government based on consensus," Adnan al-Dulaimi said.

Al-Dulaimi confirmed that Iraq's two Kurdish leaders, Talabani and Kurdistan regional President Massoud Barzani, have been mediating with other groups to form a coalition government.

Their efforts seem to have forged an understanding between the main Shiite religious bloc and al-Dulaimi's group — which represent two traditionally hostile camps whose enmity often threatens to plunge Iraq into sectarian warfare.

Shiite leaders have in recent days threatened reprisals against the minority Sunni Arabs following twin suicide attacks that killed more than 100 people. They have blamed the attacks on both the Sunni-Arab-led insurgency and some Sunni Arab political groups they say openly support the militants.

"This should be done by consensus for the sake of Iraq's unity and independence. Barzani, Talabani and I agree on this condition, and this is our sole condition and demand," al-Dulaimi said.

Talabani said Saturday that Iraq's political groups could form a coalition government within weeks — and some experts say the new government could be formed next month.

"Barzani and Talabani are conducting contacts with the Shiite Alliance and I think that the Alliance should agree on this project otherwise stability in Iraq cannot be achieved," al-Dulaimi said of a broad-based government.

Forming a viable broad-based government is a key American goal because such an administration, if it includes Sunni Arabs, could help defuse the insurgency.

In an effort to help draw Sunni Arabs into the political process, U.S. officials for months have been communicating directly or through channels with members of the disaffected minority connected to the insurgency.

The Iraqi government also said it was talking directly to all militant groups who are willing to communicate, but no commitments have been made to any of them, said Wafiq al-Samarie, an adviser on security affairs to Talabani.

"Yes, many groups are communicating with us. We are listening to them and providing them with advice with open arms and transparency," said al-Samarie, a Sunni Arab and a former intelligence chief under Saddam Hussein.

Sunni Arabs expressed anger over a raid by U.S. troops on the headquarters of the Association of Muslim Scholars, a major Sunni clerical group.

The troops raided the headquarters of the association, thought by some to be close to some terrorist groups, at Baghdad's Umm al-Qura mosque before dawn Sunday.

"The Americans bear the responsibility for this assault," said Sheik Younis al-Ekaidi. "This crime came as punishment for the association's position on the occupation and its position on the latest elections."

A U.S. military official said the raid came after a tip from an Iraqi citizen that there was "significant terrorist related activity in the building," and six people were detained.

In other violence Sunday, according to Iraqi police:

— Gunmen assassinated a member of former Prime Minster Ayad Allawi's secular Shiite Iraqi National List in Baghdad.

— A gunman was killed when clashes broke out between militants and Iraqi police.

— Militants opened fire on a vehicle in Baghdad, killing the driver.

— Gunmen killed a policeman in western Baghdad.

— Police found six bodies, most shot in the head, at a sewage plant in southeast Baghdad.